## Friday, March 21, 2014

### Game Description: Yavalath

Last semester, I stumbled on the game Yavalath while browsing reddit.  This game is especially exciting because the rules are very similar to tic-tac-toe type games... except for an excellent twist!

Yavalath is played on a hexagonal board.  Each turn a player paints an empty hexagon their color.  So far, no twist.

If you get four hexagons in a contiguous line, you win.  No more moves are played.  Still no twist.

However, you are not allowed to play in such a way that you get exactly three hexagons in a row.  More than three is fine (and you win) but exactly three is not allowed.  Twist! :)

One problem keeps this from being strictly combinatorial: the board can fill up so that neither player wins.  In this case, you could just announce that the last player is the winner since no more moves exist.  The site gives an example of such a case:

Notice that this position would probably be the result of a sum, as there are an even number of white and black pieces.  Cool!

This is a game Cameron Browne generated with the program Ludi.  I know nothing about automatically generating rulesets, except that it seems to have worked out here.  Yavalath is very fun to play.  I challenged many of my students to quick games before class, and also over lunch.

1. Wow, 2 years since I did a "game desription" post. Oops!

2. Yes, Yavalath is cool, and easy to teach. Also works 3-player. Try out Pentalath too, playable with the same equipment and also invented by the program Ludi.

3. Added Yavalath to the Ruleset table:

http://cs.colby.edu/kgburke/rulesetTable.shtml

4. Anonymous, I've played Pentalath also and enjoyed that game as well. I don't quite consider that a variant of Yavalath, as it's quite different. Do you agree?

5. I'm excited to try out Yavalath. It seems simple enough to get my kids into. I'd love to find out more about Ludi, and what metrics define a 'good game', but I haven't found much out there.

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7. Glad you're enjoying Yavalath! One thing about the rules though: players ARE in fact allowed to make a losing line of 3. This has a fundamental impact on the end game if neither player has managed to make a winning line of 4, as one player will eventually be forced into making a cold (losing) move as the board fills up. This makes draws extremely rare.